1. Field of the Invention
The invention relates to a new type of absorber for a solar collector.
It is known that flat solar collectors, also called "insulators", comprise a heat absorption means, most often a metal sheet, equipped with a system for removing the heat by means of a heat-carrying fluid, generally water or air. Such an absorber is usually protected by glazing in front of its face exposed to the solar radiation whereas a heat insulator is disposed therebehind.
2. Discussion of the Prior Art
A widespread type of absorber is formed from two stamped metal sheets, joined together by welding, so as to define therebetween a volume in which flows water serving as a heat-carrying fluid. Such an absorber involves however the use, for stamping the metal sheets, of high-power presses, which involves high investments costs, especially for small- or medium-scale manufacture, and increases considerably the manufacturing costs.
To avoid this disadvantage, it has been proposed to construct the absorber by means of two flat metal sheets, joined together by welding at their periphery, and connected by a number of spot welds distributed over the whole of their surface or by means of parallel welding beads, the metal sheets thus joined together being then shaped by exerting directly a hydraulic pressure by means of water injected between them. Such a manufacturing process has the advantage of being simple in principle, but it presents nevertheless serious disadvantages, not only from the manufacturing but also from the user point of view.
In fact, during the shaping of the metal sheets, it is difficult to control the deformation thereof, except by using a table for holding them in place thus limiting the deformation. Now, such tables are necessarily heavy, for they must resist the considerable thrust which is exerted thereon by the absorbers during their shaping. They are then difficult to handle and their use complicates the manufacture, all the more so since the water feeds to the absorber make it difficult to automate the different operations.
But, furthermore, during use, this type of absorber is not without disadvantage. In fact, if the deformation of the metal sheets has not been perfectly symmetrical, the absorber risks being subjected to a general deformation. Furthermore, the welding points present a permanent risk of breakage, for they are subjected to wrenching forces, because of the deformation of the metal sheets in their vicinity. In fact, the parts of each metal sheet surrounding the welding points tend to move away from one another, not only in parallel, under a general effect of the pressure, but also because of progressive detachment due to the distortion of the metal sheets which, not having been stamped, tend to become deformed.